Magnetic recording apparatus



g- 15, 1950 L. B. GREENLEAF ETAL 2,51

MAGNETIC RECORDING APPARATUS Filed Oct. 20, 1944 e I i Patented Aug. 15, 1950 PATENT c--Armom Research -Foundatioz3 3 of Illil10i5- Institute of l ec'hnolng'y', Chicago; Ill.,-a.oorpora,tion

s of'lllinois .-r I-hissinv ention' reiatesito magnetic -reco'rdin'g apparatus 'andnmore ipanticuianly to apparatus for recording "arse-producingsounds magnetioally from a smallcwire. r

' sl mreoording or rreproduoingfapparatus ot the type e'rriployinga *magnetized wirm difficulty-has been enoountefed in threading the-wise through by an operator-so that thewi-re may' be broken or damaged as for exampla byskinking it.

One of the objects of the zpresent -invention is to'wproduoe magnetic --re'oording apparatus in which-spools of :wire man easily-be inserted withoutlreqdiizingrthait thesvire be "threaded through I therapparatus, I

Another object: of the invention is 430 provide magnetic recording appasatu uin whieha leader is l-permanently attached to the :take-upspool of the apparatus :and is left threaded-through therecording -or reprodueinguparts of theapparatus when the supply--spooi-is remove-d. Y

Still another object is to provide magnetic --recording apparatus "in the driving motor is shut ofli during a ire-winding operatioa when "the leaderon thetah'ewphpodi starts to unwind therefrom. i

The above and other objects andadvantages of the-invention wililoe more readily apparent from the 1 following desopiption when .read in connection withi the aocompanying drawing in which: l e i A I v Eigtt-Fe l is a diasramma-tic view of one 40mm.

t {apparatus embodyingthe invention; Figure 2 is anwenlarged .partiall -side :viewicif the takeeap .=1'ee1 of Figure l; i Y

Figure 3' is an enlalrged .partialasedtion on the line G e-80f Figure 2;

Figure 4 is; an enlaizgedarsedtional- View or a couplihgtand 'r Figure 5 -ispa-di'agramss'i nii'lan sim flar to Figure 1 showing an alternative motor control.

I-he apparatus of Figure lcomprises. 'a suppiy spool 1| mwh-i-ch inlay-be the apparatus and oarries a this metal wire 'of magnetic :material on whieha fecord ing' has beenmr--is to:be#made; dimermanentiy mounted" take-:upreel H is carried-shy the aiz paratus and is adapted to i receive thdwire mam the supplyaspool during operation. The spools are adapted to -be driven in' anywdesired mam ner; to transfer the wirer from one t'o the dthe'i'; butlpreferably the speed (if-the wire is controlled by'a d1=iving:pu1ley t2 driven 'by a motor 13 50 that :the :speed of the wire will -be substantially constant regardless ofthe'amount w'hich -is wound on the spools. As shown diagrammatically the spools are driven by-themotor 3 through 'a filotior wheel 8 which engages the-spools. The wire as r shown passes over -g-uide l-pulleys --l 4 throughn magnetic head 45 which may-either impvss a m'agnetio record on the wire or which may "be n. reproducing-head to take off a eprevious-reoord ing fromthewire. It will be understood tliat in addition to the-parts-shownperasi g headsan'd sound producing or translating devices -may employed as is standard in the art, Y v --Acoording to -thepreseptinvention, when'a. fresh supply spool is '-inserted in the :maoh-ine it is unnecessary for the operator to thread the wire thereon over the variousp llleys andthrough the head 15 For this purpose a leader- "416 15- permaner tly attached at one; end to the talgeup 59061 H and is of sueh'afllength that it will extend over the several vlpul-levs and through the head and will terminate adjacent the s mply spoo T0. At its free end the leader carries/ a couyi ing T1 bv which it may be connected-to the wire on't'he .sumily sno'ol. Instead of conneotin'e the leader directlv to Ithe wire, itirialy "be preferred "to I-provifie a'leader permanenltly 'at-. tahed "to the wire itseIf to which the coiiiili n'g 11 may be connected.

Any: -desired type of couplihg for: conneting the-Header "T6 "to the Wife- 'or'to a leader there onmay be emoloyed. For site-mole, a fco ipiing o'f the ty e used in key chains or on va;riou s types of jewelry. siieh as nscklsoesgmaybeuses satisfactorily. 'onetype of bre'ferred' ooi jil-fiig, is illustrated in Figure 4 and inelodes a -hoirow body 1B hav'ing a' forwardly tap'e'ri g opening therein. The "body is is se'our'ed 'to th'e tiid'jdf the lesser leana "has on its Interior a, 's'lidalfile W'Eti'g'e -f9 with a handle 20 thereon 'iidi i'ig through alsldt in the "may. The wire 0 de r oii'the wire, as in'dioat'ed at Z' IfmaYbe inSertd wedge into the large part of the body so that it will not grip the wire.

If the leader were wound on the main body of the take-up spool during a take-up operation, the wire which may be of a difierent diameter than one or both leaders might tend to jam around the leader or around the coupling. This might result in damage to the wire and it certainly produces unevenness of motion as the wire is wound on the take-up spool. Inorder to eliminate these difiiculties the spool I l is formed with an enlarged flanged end 22 to which the leader I6 is attached. The end 22 is formed with a spiral groove 23 in which the leader will be wound as the spool is turned. It will be understood that the width of the end 22 and the total length of the groove 23 are such as to receive the full'length of the leader l6. At the point where the connector l1 will wind onto the end 22 an enlarged recess 24 is provided to receive the connector. Beyond this point the face of the end portion 22 maybe cut to form a slopingshoulder 25. As the take-up spool is rotated to wind up the leader I6 and the' wire, the leader will be wound in the groove 23 and the connector ll will fall into the recess 24. Upon further rotation the wire or the' leader connected thereto will wind on the sloping shoulder 25 and will thereafter be wound directly on the reduced body portion of the spool. Thusthe wire may be wound smoothly on the spool without danger of jamming.

' In rewinding the Wire from the take-up spool llfback onto the supply spool Ill, it is desired to interrupt operation of the driving motor l3 before the leader is completely unwound from the take- 1 u'p'spool so that the apparatus will stop with the connector I! in the desired position. It will be understood that the spoolsare driven by the motor [3 through a yielding drive mechanism which will permit slight variations in the speed thereof whilethe speed of the wire is held substantially constant by the driving pulley l2. As shown in Flgurel, the motor is controlled by a shut-01f switchincluding a contact 26 and a switch arm 21 which opens the motors circuit when the arm is pulled down. The arm 21 carries a magnetic core which will be attracted by a relay coil 28 when the coil isenergiz ed. The coil 28 is connected in ciredit with a source of current such as a battery Z9 and with a tube 3| having acathode 32 connected to one side of the coil and a plate 33 connected to the other side of the coil. The tube is controlled by. a grid 34 which is connected to one of the guide pulleys I4 and the other guide pulley I 4 "is connected through a biasing battery 35 to the cathode. The pulleys M. in this construction are insulated from each other. The leader lt may. be made of a non-conducting material while the wire on which the recording is, dris to be made, will be conductive. Therefore when'the wire is wound on the spool II, it will extend from the reel l0 around the pulleys I4 and guidepulley l2 to complete a circuit between the pulleys I 4 through the wire itself. At. this time the, battery 35 will be connected to the grid 34 to bias it beyond cut off so that the tube 3| will not conduct and the coil 28 will be deenergized. As wirels rewound on the supply spool 16, the noncqn ducting leader eventually starts. to unwind from the take-up spool .H and when the leader engages the first of the guide pulleys M, the circuit between the guide pulleys will be interrupted. At this, time the negative bias will be removed from thegrid 34 of thel ube so that the tube will start to conduct and will energize the coil 28. The

arm 21 will thereupon be pulled down to Open the switch 26 and stop the operation of the motor. The apparatus will have sufiicient inertia so that the leader [5 will continue to be unwound from the take-up spool l I and the apparatus will coast to a stop with the connector I! in substantially the position shown. If the reels and pulleys should attempt to coast beyond this position, their operation will be stopped by the leader itself when it is .fully. unwound from the take-up spool as shown.

An alternativemotor control arrangement is shown in Figure 5 in which figure parts corresponding to like parts in Figure 1 are indicated by the same reference numerals. In this construction a switch 36 having an operating arm 31 is mounted adjacent the take-up spool l l and is connected to the drive motor to control it. During the normal recording or reproducing operation and the first part of the rewinding operation the wire beingwithdrawn from the take-up spool will occupy the position shown by the dot dash 'line'and the operating lever 31 will be in its dotted line position with the switch 36 closed. As soon as the leader I6 starts'to unwind from the spool, the wire and leader will be moved to the full line position due to the fact that the leader is being unwound from the larger diameter end 22' of the spool. The switch operating lever 3'! will therefore be moved to its full line position to open the switch 3'6 and interrupt the operation of the motor. It will be understood that control switches parallel to the switches 26 or 36 may be provided to control operation of the motor during a normal recording or reproducing operation.

While two embodiments of the invention have been shown and described in detail, it will be understood that'thes'e are illustrative only and arenot to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is: "1. Magnetic recording apparatus comprising a take up spool, a supply spool adapted to contain awire, a magnetic head through which the wire to thesupply spool, a detachable coupling on the leader for connecting the leader to the wire onthe supply spool, a drive motor to Wind wire from the supply 'spool on the take up spool and to rewind wire from the take up spool on the supply spool, and means engaging and controlled by lthe'wire and leader at a point spaced from the take up spool to interrupt operation of the motor when the leader starts to unwind from the take up spool.

2. Magnetic recording apparatuscomprising a supply spool adapted to contain a wire, a take up spool,'a leader of non-conducting material permanently attached to the take-up spool, a connector on the leader for detachably connecting it to the wire a head through which the wire and leader'pass between the spools, spaced contact members engaging the wire and the leader, a drive motor to drive the spools, control means for the drive motor, and means for operating the control means connected to the contact members and responsive to electric connection and disconnection of the contact members by the wire and the leader. I

3. Magnetic recording apparatus comprising a supply spool adapted to contain a wire, a take up spool, a leader "of non-conducting material permanently attached to the take up spool, a connector on the leader for detachably connecting it to the wire, a head through which the wire and leader pas between the spools, spaced guide pulleys over which the wire and leader pass between the spools, a drive motor to drive the spools, and a control circuit for the drive motor connected to the guide pulleys to energize the motor when the wire engages both pulleys and to deenergize the motor when the leader engages one of the pulleys.

4. Magnetic recording apparatus comprising a supply spool adapted to contain a wire, a take up spool, a leader of non-conducting material permanently attached to the take up spool, a connector on the leader for detachably connecting it to the wire, ahead through which the wire and leader pass between the spools, the take up spool including parts of difierent diameters on which the wire and the leader are Wound, a drive motor, and a control switch for the motor having an operating part engaging the wire and leader adjacent the take up spool to operate the switch when the leader starts to unwind from the take up spool.

5. Magnetic recording apparatus comprising a supply spool adapted to contain wire, a take up spool having a reduced central portion with ends of increased diameter, a leader connected to one of the ends of the take up spool and adapted to be wound thereon, and a connector on the leader to connect it to the wire.

6. Magnetic recording apparatus comprising a supply spool adapted to contain wire, a take up spool having a reduced central portion with ends of increased diameter, a leader connected to one of the ends of the take up spool and adapted to be wound thereon, and a connector on the leader to connect it to the wire, said'one end of the spool being formed with a spiral groove to receive the leader and having an enlarged recess to receive the connector so that the leader will be wound on the end and the wire will be wound on the reduced central portion.

7. A spool for magnetic recording apparatus comprising a cylindrical spool body having enlarged flanged ends, a leader permanently secured to one of the ends, and a connector on the leader, said one of the ends being formed with a spiral groove in which the leader may be woundand which terminates in a sloping portion leading to the spool body. a

8. A spool for magnetic recording apparatus comprising a cylindrical spool body having enlarged flanged ends, a leader permanently secured to one of the ends, a connector on the leader to connect it to a wire to be wound on the spool, said one end of the body being formed with a spiral groove to receive the leader and having an enlarged recess to receive the connector so that the leader will be wound on the flanged end and the wire will be wound on the spool body.

9. In magnetic recording apparatus, a spool comprising a cylindrical spool body to receive a strand and having end flanges of greater diameter than the body, one of the end flanges being formed in its outer surface to receive a strand and having a sloping shoulder on its inner face leading to the spool body and a control device having an operating part engaging a strand on the spool adjacent to the spool to be moved by the strand as it moves along the shoulder.

10. In magnetic recording apparatus, a spool comprising a cylindrical spool body to receive a strand and having end flanges of greater diameter than the body, one of the end flanges being formed in its outer surface with a spiral groove to receive a strand, the groove terminating at the inner face of the flange in a sloping shoulder leading to the spool body to direct a strand from the flange to the spool body and a control device having an operating part engaging a strand on the spool adjacent to the spool to be moved by the strand as it moves along the shoulder.

11. In magnetic recording apparatus, a spool comprising a cylindrical spool body having end flanges of greater diameter than the body, one of the end flanges being formed in its outer surface with a spiral groove to receive a leader, and the groove having an enlarged recess therein to receive a connector on the leader.

LELAND B. GREENLEAF. EARLE L. KENT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

